Ischemia can result from various physiologic events including myocardial infarction, abnormal cardiac rhythms such as tachycardia, bradycardia, etc., blood clots, atherosclerotic plaque rupture, coronary artery spasm and other blockage causing events. Ischemia can also result from certain medical procedures that involve temporary attenuation or obstruction of blood flow.
Mitochondria are essential organelles present in all nucleated cells whose main function is the generation of cellular ATP by oxidative phosphorylation. Mitochondria are also involved in a number of cellular pathways, including calcium homeostasis, apoptosis, heme biosynthesis, and cell signaling. The size, shape, and structural organization of mitochondria, as well as the number of these organelles per cell and their intracellular location, vary considerably depending on the organism, tissue, and physiological state of the cell examined. In the myocardium, mitochondria can constitute 30% of the total myocardial cell volume.
The human mitochondrial genome is a 16,569 base pair circular molecule. It consists of two strands, a guanine-rich strand (H-strand) and a cytosine-rich strand (L-strand).
It has been found that temporary attenuation or obstruction of blood flow can negatively alter myocardial mitochondrial structure and function. These structural and functional changes can persist even after normal blood flow resumes and can lead to decreased myocardial contractile function and myocardial survival.